Current Replication Circuit with Segmented Bias and Sensing Paths
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Solution Overview
Problem
Traditional current sensing and replication circuits are limited by speed due to closed-loop configurations, which is undesirable in high-speed switching applications, and often require additional sense elements for bidirectional sensing, complicating the circuit design.
Innovation Solution
The proposed solution involves a current replication circuit with a bias circuit and transconductance amplifier, where the first transistor is sized relative to a second transistor according to a scaling factor, and the transconductance amplifier is set in a closed-loop arrangement to control the quiescent bias point, generating an output sense signal in an open-loop configuration, allowing for bidirectional sensing without additional sense elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional closed-loop current replication circuits are used, then stability is maintained, but speed is limited
Solution Approach 1:
The patent segments the current replication function into two distinct paths: a closed-loop path for stability (biasing the transconductance amplifier) and an open-loop path for speed (actual current sensing and replication). This segmentation allows each path to be optimized for its specific function without compromising the other.
Solution Approach 2:
The patent performs preliminary action by establishing the quiescent bias point of the transconductance amplifier through closed-loop feedback before the actual current sensing operation. This preliminary biasing ensures stability is pre-configured, allowing the subsequent open-loop sensing to operate at high speed without stability concerns.
2Adaptability or versatility
If additional sense elements are added for bidirectional sensing, then sensing capability is improved, but device complexity increases
Solution Approach 1:
The patent makes the existing sense element and transconductance amplifier multi-functional by configuring them to handle both positive and negative current directions through appropriate transistor sizing and biasing. The same hardware infrastructure performs bidirectional sensing without requiring duplicate sense elements, thus maintaining versatility while avoiding increased complexity.
Solution Approach 2:
The patent merges the bidirectional sensing capability into the existing current replication circuitry by using the same sense element and transconductance amplifier for both directions of current flow. This consolidation eliminates the need for separate sense elements for each direction, reducing device complexity while maintaining full bidirectional functionality.
Data Source
AI summary
A current replication circuit includes a bias circuit and a first transistor sized, relative to a second transistor to be sensed, according to a first scaling factor, the first transistor having an on-resistance associated therewith. The current replication circuit further includes at least one transconductance amplifier having first and second signal paths. The first signal path is connected with the bias circuit in a closed loop configuration such that a quiescent bias point of the transconductance amplifier is controlled as a function of the on-resistance of the first transistor. The second signal path is connected with the second transistor in an open loop configuration and is adapted to convert a sensed input voltage to a corresponding current output signal as a function of the quiescent bias point of the transconductance amplifier, the current output signal being proportional to a current flowing through the second transistor.